A synchronizer ring is a ring-like member which is incorporated in a transmission of an automobile and which, at the time of a gear shifting operation of the transmission, synchronously rotates two gears so that the two gears which are engaged in the shift can be smoothly engaged with each other. Characteristics required for the synchronizer ring are, among others, (1) that the coefficient of dynamic friction with respect to a mating member is large in order to synchronize two gears by frictionally engaging a tapered portion which is the mating member, and (2) that the synchronizer ring has wear resistance in sliding with the mating member and the like.
Patent document 1: JP-B-7-107182
Patent document 2: JP-B-47-24053